Many modern telecommunications systems, computer systems and the like transmit and/or process both electrical signals and optical signals. Typically, optical signals are routed via optical fibers over relatively long distances in order to increase the transmission speed and efficiency relative to the propagation of electrical signals. In contrast, much of the signal processing analysis and storage is performed electrically. Thus, these systems must frequently convert optical signals to electrical signals, and electrical signals to optical signals.
Many modern telecommunications systems, computer systems and the like include a number of printed circuit boards or cards which plug into a back plane or mother board. As known to those skilled in the art, the back plane generally provides power as well as a reference voltage or ground to each of the printed circuit boards. In addition, the back plane provides a pathway by which the printed circuit boards communicate with each other.
Signals can be routed along the back plane either electrically or optically. If optical signals are routed along the back plane, the optical signals must generally be converted to electrical signals upon delivery to the printed circuit boards since the printed circuit boards typically include a number of electrical components for processing electrical signals.
In order for the printed circuit boards to plug into the back plane, at least one edge of each printed circuit board includes a number of electrical contacts for establishing electrical connection with corresponding contacts defined by the back plane. In order to establish optical communication with one or more of the optical fibers routed along the back plane, the printed circuit board can also include one or more optoelectrical converters which as either a transmitter or a receiver. For example, an optoelectrical converter receives optical signals and converts those optical signals into corresponding electrical signals prior to routing the electrical signals about the printed circuit board. Instead, the optoelectrical converter could convert electrical signals into corresponding optical signals prior to routing the optical signals along the back plane.
As will be apparent, however, a separate optoelectrical converter is necessary for each optical fiber which is routed to the printed circuit board. If very many optoelectrical converters are mounted along the edge of the printed circuit board, the optoelectrical converters will consume a significant portion of the edge. As a result, the number of other contacts, such as electrical contacts, that can be established at the edge of the printed circuit board will be reduced as the number of optoelectrical converters positioned along the edge of the printed circuit board increases.
Attempts to interconnect optical fibers to the printed circuit board at locations other than the edge of the printed circuit board that plugs into the back plane have disadvantages. Notably, the interconnection of one or more optical fibers to the printed circuit board at a location other than the edge of the printed circuit board which plugs into the back plane will generally hinder the insertion and removal of the printed circuit board since the optical fibers must typically be separately handled to prevent tangling. In this regard, fiber management is becoming of ever increasing importance to a system designer as the number and lengths of the optical fibers increase. As a result, system designers generally strive to control the routing of the optical fibers so as to prevent the optical fibers from interfering with other components or from otherwise causing congestion.